Apparatus for dispensing a metered amount of fluid

ABSTRACT

Dispenser apparatus including a container configured for retaining a source of liquid and having a plurality of deformable wall portions which may be selectively activated by an external force so as to reduce the volume of the container and thereby provide repetitive application of a given pressure to the retained source of liquid for dispensing of the liquid from the container. Preferably, a plurality of the wall portions are configured for irreversible deformation so as to permit successively reduced volume in accordance with their actuation and at least one is configured for reversible deformation and is biased to return to its original position upon removal of the actuating force thereby returning any excess of the dispensed liquid to within the container.

ljite 1 tes Lehmann APPARATUS FOR DHSPENSING A METERED AMOUNT 0F FLUID[75] Inventor: Walter G. Lehmann, Somerville,

Mass.

[73] Assignee: Polaroid Corporation, Cambridge,

Mass.

[22] Filed: June 5, 1972 [21] Appl. No.: 259,388

Related us. Application Data [62] Division of Ser. No. 103,986, Jan. 5,1971, Pat. No.

52 us. C1 222 209, 222/336, 222/405, 401/184,118/266 51 lint. c1 ..B65d37/00 [58] Field of Search... 222/207, 209, 2 05, 213, 187, 222/269,338, 335, 336, 318, 405; 401/196, 183, 184, 185, 264; 95/94 R; 118/266,264, 401

[56] References Cited UNITED STATES PATENTS 2,643,408 6/1953 Decker401/183 Leet et a1 401/184 3,685,412 8/1972 Lehmann 222/213 X 1,928,2359/1933 Taylor 95/94 R 3,018,756 1/1962 Kilham t i t 118/264 X 3,133,4845/1964 Wright 118/264 X Primary Examiner-Stanley H. Tollberg AssistantExaminer-1ames M. Slattery [57] ABSTRACT Dispenser apparatus including acontainer configured for retaining a source of liquid and having aplurality of deformable wall portions which may be selectively activatedby an external force so as to reduce the volume of the container andthereby provide repetitive application of a given pressure to theretained source of liquid for dispensing of the liquid from thecontainer. Preferably, a plurality of the wall portions are configuredfor irreversible deformation so as to permit successively reduced volumein accordance with their actuation and at least one is configured forreversible deformation and is biased to return to its original positionupon removal of the actuating force thereby returning any excess of thedispensed liquid to within the container.

12 Claims, 10 Drawing Figures APPARATUS FOR DISPENSING A METERED AMOUNTOF FLUID RELATED APPLICATIONS This application is a division ofapplication Ser. No. 103,986, filed Jan. 5, 1971, now US. Pat. No.3,685,412.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to dispenser apparatus and more particularly to an improveddispenser adapted for repetitively dispensing processing fluid tophotographic material.

2. Description of the Prior Art In modern technology, it is oftendesirable to simply and efficiently apply processing liquids during aparticular operation. For instance, as noted in the parent applicationfollowing exposure of photographic material, it is usually necessary tosubject it to a suitable processing liquid for a prescribed imbibitionperiod. Generally, it is important to minimize the amount of processingliquid employed and to dispense the latter with a minimum of entrappedgas. Since the processing liquid employed is generally corrosive it mustbe suitably confined so as to protect both the apparatus and theoperator. Moreover, application of the processing liquid in portableapparatus with which the present invention is particularly concerned,further compounds the difficulties of storing and applying the liquidsince this often requires the application of predetermined quantities ofthe liquid, uniformly and at relatively high rates, and the necessityfor so doing in apparatus that may be operated manually and presents theproblem of precluding spillage.

Accordingly, it is an important object of this invention to provideimproved apparatus for dispensing fluid.

Another object of the invention is to provide apparatus for repetitivelydispensing a predetermined quantity of processing liquid. 7

A further object of the invention is to provide an applicator forefficiently dispensing a predetermined amount of gas-free processingliquid uniformly over sheet-like material.

A still further object of the invention is to provide apparatus forrapidly applying processing liquid to photographic material.

SUMMARY OF THE INVENTION Broadly, the apparatus comprises a container ofpredetermined volume configured for retaining a liquid and includesmeans configured for successively decreasing the container volume andegress means for permitting dispensing of the liquid in accordance withsuch reduction of volume. Preferably, the egress means comprises porousfilter material which, within a given range of pressure differential, isliquid permeable and gas impermeable such that gas-free processingliquid may be substantially uniformly dispensed over the filter surfacein accordance with operation of the volume decreasing means.

In the illustrated embodiment, the dispenser is em ployed in a camerastructure for applying processing liquid to a photosensitized sheet ofphotographic film and is configured to dispense to the film a prescribedamount of processing liquid from a source thereof and, following anappropriate imbibition period, to return any excess liquid to thesource. In this arrangement, the container includes a plurality ofdeformable wall portions, each adapted to reduce the container volumeand thereby increase the source pressure by a prescribed amount inaccordance with inward displacement of the wall portions responsive toapplication of an external force. One of the discrete portions isadapted for reversible deformation for repetitive dispensing of theliquid from the container upon application of the external force andreturn of any excess liquid upon removal of such force. The remainder ofthe deformable portions are adapted for irreversible displacement so asto maintain a substantially constant source pressure intermediaterepeated applications of the liquid. In this embodiment, the containerbody is constructed of material which, while capable of providing asubstantially rigid container of fixed volume is sufficiently elastic topermit displacement of thin wall portions. Each of the discrete wallportions are substantially rigid portions of the same wall thickness asthe body of the container which are coupled to the latter by a thin wallportion so as to provide a diaphramlike member. Additionally, theelasticity of the thin wall section surrounding each portion tends tobias each portion to its original position. This is utilized in regardto the one reversible por tion but circumvented in the ease of theirreversible portions which include means for automatically latchingthem in their depressed position.

I BRIEF DESCRIPTION OF THE DRAWINGS The novel features that areconsidered characteristic of the invention are set forth withparticularity in the appended claims. The invention itself, however,both as to its organization and its method of operation together withadditional objects and advantages thereof will best be understood fromthe following description of the preferred embodiment when read inconnection with the accompanying drawings wherein like numbers have beenemployed in the different figures to denote the same parts and wherein:

FIG. 1 is a diagrammatic view in perspective of a photographic cameraembodying the invention;

FIG. 2 is a diagrammatic view partially in section illustrating one filmmagazine employed in the camera of FIG. 11;

FIG. 3 is a diagrammatic view partially in section showing another filmmagazine employed in the camera of FIG. 11;

FIG. 4 is a diagrammatic view in perspective illustrat ing theprocessing station of the camera;

FIG. 5 is a view in section of the processing station taken along line55 of FIG. 4;

FIG. 6 is a diagrammatic view in perspective of another operativeelement of the camera; and

FIGS. 7, 8, 9 and 10 are diagrammatic plan views of the interior of thecamera and illustrating its operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of thisinvention is illustrated as a camera including apparatus facilitatingapplication of a compatible processing liquid to a photosensitiveimage-recording sheet following its exposure and superposition of thissheet with an image-receiving sheet for formation of a visible image inthe latter by a diffusion-transfer process. The apparatus and process ofthe invention while applicable to photography in general, is speciallyadapted to produce photgraphic transfer prints such as those describedin US. Pat. No. 2,983,606 issued May 9, 1961 to Howard G. Rogers andutilizing integral multilayer image-recording sheets incorporating dyedevelopers such as are disclosed in US. Pat. No. 3,345,163 issued Oct.3, 1967 to Edwin H. Land et al., and to photographic film processing asdescribed in US. Pat. No. 3,485,628 issued Dec. 23, 1969 to Edwin H.Land. As indicated in the latter patent, the multicolor image-recordingsheet isfirst photoexposed to form a latent image, then permeated withan aqueous alkaline processing liquid, and finally, superposed with animage-recording sheet so as to produce a visible image therein.

As shown in FIG. 1, the apparatus provides a camera having a housingproviding a substantially light-tight structure including a conventionallens and shutter assembly 12 at the front thereof adapted to expose aphotosensitive sheet presented at an exposure aperture 14. Releasablymounted at the left and rear sides of the housing 10 are film magazines16 and 18 which supply the photographic sheets utilized in the camera.At the right side of the housing is a processing station 20, and

the interior of the housing includes a transport mechanism 22 providingmeans for transport of sequential image-recording sheets 24 frommagazine 16 to aperture 14, processing station 20 and to a rear section21 of the camera where each is superimposed with a suitableimage-receiving sheet 42 from magazine 18, as later explained in detail.

As shown in FIG. 2 magazine 16 provides means for storing and dispensingimage-recording sheets 24. The sheets 24 are disposed within magazine 16in a stacked relation and urged towards the upper face 25 of themagazine 16 by a pressure plate 26 in cooperation with a spring member27 such that the uppermost sheet of the stack is positioned in alignmentwith an exit aperture 30 of the leading edge 28 of the magazine. A sheetengaging member 32 extends from the magazine 16 and is adapted fordisplacement towards the leading edge 28 for lateral ejection of theforemost sheet through aperture 30. Advantageously, sheet engagingmember 32 may be spring biased by any conventional means (not shown) ina direction away from aperture 30 so as to provide automatic return tothe engaging position following film ejection. Integral with themagazine I6 and extending from its leading edge 28 are a pair ofextended arms 36 configured for releasable mounting of the magazine tothe housing 10. Hence, arms 36 are designed to releasably engage post 38of the housing 10 to permit pivotal movement of the magazine 16 to aclosed position as shown in FIG. 1 where it is retained by anyconventional locking means (not shown). In this position, edge 28 of themagazine adjoins the exposure aperture 114 within the housing 10.

Magazine 18 which is mounted at the rear of the camera, provides meansfor storing and dispensing of the image-recording sheets 24 inaccordance with operation ofthe apparatus and, as shown in FIG. 2,contains a plurality of the image-recording sheets in a stacked relationwith the lowermost of these sheets laterally aligned with an exitaperture 44. A pressure plate 46 in cooperation with a spring 48 urgesthe film stack towards the lowermost face 51), as shown in this figure.

Slideably mounted within magazine 18 is a film engaging member 52 whichincludes a flexible tongue 54 adapted to drive each successive filmsheet in a direction opposite to the displacement of the engagingmember, or that is, to move the lowermost film sheet through aperture 44as the engaging member is displaced in a direction away from thisaperture. This is accomplished by any conventional means such as byconfining tongue 54 within a track or channel (not shown) so as to forceit to bend back on itself. The unit is completed by integral mountingarms 56 which extend from the leading edge 58 of the magazine forreleasable pivotal mounting to housing It), for example, by engagementwith post 59 of the housing as shown in FIG. 1. A conventional latch(not shown) is employed to releasably secure the magazine 18 in a closedposition with its exit aperture 44 located adjacent the feed rolls ofthe camera for dispensing of each imagerecording sheet 42 thereto, aslater explained in detail.

Processing station 20, as shown in FIGS. 4 and 5, includes a demountableapplicator unit 60 which is configured for releasable mounting tohousing 10 in an adjoining relationship to a film support member 62. Theapplicator unit 60 is made up of a box-like housing 64 which is closedat its open end by an applicator body 76. This forms a narrow cavity orinternal chamber 66 of predetermined volume between the rear wall 74 andbody 76 for containing a source of processing liquid 68.

Preferably, applicator body 76 is a substantially inflexible member ofporous material which facilitates delivery of gas-free liquid fromsource 68 to the exterior surface 78 of the body. Hence, the body 76provides egress means for permitting dispensing of the liquid 68 fromthe chamber 66 to the exterior of the housing 64. The exterior surface78 is of slightly greater area or dimension than that of exposureaperture 14 whereby all of the photoexposed area of each film sheet maybe disposed in contact with the applicator surface at a given time.

The body 76 is of so called membrane filter material, that is,microporous material having a sponge-like structure of smallinterconnected pores which provide, a relatively high bubble pressure inthe processing liquid, and hence, in cooperation with the surfacetension of the liquid, preclude passage of gas up to relatively highpressure. Substantially coplanar with the applicator surface 78 is asealing member of perimetric gasket 79 of 40 durometer rubber or thelike which provides a rectangular surface enclosure and is intended toengage the perimetric margin of the film sheet 24 exteriorly of itsphotosensitive area.

Suitable membrane materials are glass, ceramic, car bon or plastic suchas nylon or polyvinylchloride or other materials which are chemicallyinactive with the processing liquid and have a sufficiently small poresize, for example, V2 micron to 10 microns diameter such that oncecontacted with the liquid it will pass the same while excluding passageof gas upon application of a low pressure differential to the body. Thatis, the applicator body is of a substance having sufficiently small poresize, which once contacted by the liquid, is liquid permeable butsubstantially gas impermeable at relatively low pressures. Inasmuch asthe applicator body 76 precludes gas passage and includes a multiplicityofinterlocking pores, it uniformly disperses liquid to its exteriorsurface 78. Stated otherwise, although the source of liquid may notprovide uniform contact with the underside of the body 76, for example,due to entrained gas in thesource, the liquid tends to be carrieduniformly throughout the body and produces a uniform distribution on thebody surface 78. Hence, the applicator body 76 provides means fordispensing fluid from source 68 to the body surface 78 and for providinga substantially uniform distribution of liquid thereat.

It will be appreciated that the unique nature of the applicator providesrapid lateral flow of gas-free liquid to the photosensitive sheet, andsimultaneously subjects all the photosensitive surface to the processingsolution. Advantageously, the unit provides a slight excess of liquidduring imbibition, then removes any remaining excess and returns it tothe source. Hence, the arrangement not only minimizes the amount ofsource needed but also removes excess liquid from the photographic sheetprior to its withdrawal from the applicator unit. This is in contrast tocapillary applicators which fail to provide gas-free wetting of the filmsheet, fail to remove excess liquid following imbibition andadditionally do not provide external control over the liquid flow.Stated otherwise, in capillary devices the fluid flow is caused byabsorption into the film of the liquid which can result in non-uniformor incomplete wetting whereas, in the present case, liquid flow iscontrolled by the applied pressure differential.

In the rear wall 74 of container 64, means are provided for varying thepressure on source 68 and for thereby providing a suitable pressuredifferential be tween the source and the exterior surface 78 of theapplicator body. These means include a plurality of movable members 82and 84' formed by discrete deformable portions of the rear wall 74, eachof which are adapted to reduce the volume of the chamber and increasethe interior pressure by a specific amount and thereby increase thesource pressure accordingly. In this embodiment, the members 82 and 84are portions of the rear wall 74 which are joined thereto by thin wallmaterial to provide diaphragmlike areas which may be depressed, fromtheir location coplanar with the rear wall, into chamber 66 to reducethe volume and increase the internal pressure of the latter. One member82 is adapted for reversible operation for providing reversible pressurevariations and is preferably, elastically coupled to the rear wall. Forexample, the container is constructed of material having some elasticitysuch that the deformable portion tends to return to its originallocation. In operation, member 82 is depressed to dispense liquid fromthe source 68 and then released to return excess liquid to the source.In contrast to member 82, members 84 are adapted for irreversibleoperation, and include an interior latch 86 for locking each in itsdepressed location responsive to engagement of the latch with recess 88.The latter members are designed for non-repetitive operation andfunction to bring the chamber back up to the original pressure followingeach operation of member 82. Hence, each of the deformable members 84compensates for the reduction in source volume (or source pressure)resulting from the absorption of liquid in each processed film sheet.

In a specific example, which is given for purposes of illustration andnot intendedto be limiting, a 4 5 inch sheet of photosensitive materialof the type disclosed in the aforementioned U.S. Pat. No. 2,983,606 wasprocessed in the described processing station which contained anaqueous, alkaline solution having a low viscosity substantially that ofwater and containing:

Percent Potassium hydroxide l0.0 N-benzyl-a-picolinium bromide 2.0Benzotriazole 3.5 Zinc nitrate 0.5

The applicator unit was constructed with an acrylic container bodyhaving an internal volume of approximately 1.5 cubic inches and amembrane filter wall of slightly greater than 3X4 inches in length andwidth. The membrane filter, which was three-sixteenth inch thick,acrylonitrile polyvinylchloride copolymer reinforced with nylon, with amean pore size of 1.2 microns and a porosity of approximately percent,formed the front of the container; and the rear of the container,included several ll inch diameter movable wall portions of rubbermaterial. All but one of the movable members included an internal latch.

A film support member 62 made up of support plate covered by an arcuatesurface layer 92 of urethane foam having a density of 10 pounds percubic foot was employed. Both the applicator filter surface 78 and thesupport plate layer 92 were perimetrically bordered by sealing margins79 and 95, respectively of rubber hav ing a durometer reading of about40. The chamber of the container was filled with the above solutionwhich permeated the filter applicator and wetted its exterior surface.

After exposure, the photosensitized surface of the sheet was positionedover the applicator surface and progressively pressed into contact withit by forcing the film support member against the rear of thephotographic material. Then, the non'latching deformable portion wasdepressed to a depth of approximately 0.050 inch which increased thesource pressure to about 5 psi and dispensed about 1 cc. of gas-freeliquid 'tdth'e photosensitive suirsee'f" w" The depressed portion washeld in its activated position for about 8 sec., then released to returnexcess fluid to the source. Immediately following this, the photographicsheet was removed from the applicator surface and pressed intosuperposition with an imagereceiving sheet for formation of a visibleimage therein.

Thereafter, one of the self'latching deformable areas was depressed andlocked in its depressed condition by its internal latch. Thiscompensated for the reduced source volume and returned the sourcepressure to approximately its original value. A second photographicsheet was then exposed and the above steps repeated to produce itsrecorded image.

Applicator unit 60 is releasably mounted on the camera housing 10 by anyconventional latching means (not shown) withits applicator surface 78disposed in juxtaposition with film support member 62 which dur' ingcamera operation, as later explained in detail, is selectively driven bylever 96 towards applicator unit 60 to press the film sheet againstsurface 78 in accordance with operation of the camera. To insurecomplete wetted contact of the film sheet with the applicator surface78, the support member 62 includes means for removing air from betweenthe interposed sheet and the ap' plicator surface. Thus, the member 62includes a support plate 90 which carries a resilient surface layer 92of compressible material such as urethane foam of 10 pounds per cubicfoot density or the like having a curved exterior surface 94 whichtapers from a raised or extended central portion towards the marginssuch that as the support plate is moved towards the applicator 60, topress the image-receiving sheet 24 into contact therewith, contactbetween the sheet and applicator surface 78 initially is a smallrestricted area which is progressively enlarged towards the edges of thestructure so as to drive air towards the sheet margin and from betweenthe sheet and applicator surface. Thus it will be recognized that theunit wipes air or gas from the applicator surface as the sheet isdeposited and then precludes gas conduction during dispensing.

Carried at the perimeter of the plate 90 in juxtaposition with gasket 79is a second perimetric gasket 95 of resiliently deformable material suchas elastomer, for example, 40 durometer butyl rubber or the like.Gaskets 79 and 95, which are of resilient deformable material andcooperate to seal the margins of sheet 24 to the applicator 60, shouldbe less compressible than the surface layer 92 so that during operationof the unit, the margins remain sealed while film sheet 24 is deflectedslightly away from the applicator surface 78 responsive to the liquidpressure. I

As previously indicated, the support member 62 and the applicator 60 aremounted at the side of the camera housing 10, as shown in FIG. 1,adjoining exposure aperture 14 such that film sheets may be disposedwithin the processing station following their exposure. The supportmember 62 is permanently mounted in the housing for movement towards theexterior surface thereof while applicator unit 60 is releasably mountedin the exterior wall of the housing with its applicator surface 78 injuxtaposition with film engaging surface 92 of the support member.

As shown in FIG. 1, film transport system 22 includes a ring gear 100which is mounted for rotation about the vertical axis of the camera inaccordance with operation of hand crank 102. Extending from ring gear100 and interiorly thereof is a lever of lug member 104 which is adaptedfor operation of the components of the camera during rotation of thering gear. Also depending from ring gear 100 is a film engaging or filmgripping member 106 which is shown in detail in FIG. 6. As shown in thelatter figure, the gripping member 106 includes a pair of coupled levermembers 118 and 122 adapted for engaging a film sheet between theirsheet-engaging surfaces 126 and 128 in accordance with actuation of arm130. In this embodiment, the gripping member 106 is biased to a normallyclosed position by spring 124, and is pivotally mounted on shaft 120beneath ring gear 100 in position for engagement of the film sheetsduring camera operation. In this regard, the gripping member 106 isspaced slightly to the right of lug 104, or that is, leads lug 104 in acounterclockwise direction looking down on the camera.

Included within the interior of the camera is a pair of upper and lowerchannels or track 114 and 116 within which the film sheet is movedduring camera operation. Additionally, a pair of feed rolls 108 and 110are rotably mounted at the rear of the housing and adapted to superposethe film sheets after imbibition. The feed rolls 108 and 110 are coupledto the gear ring 100 by conventional means (not shown) and rotatedtherewith.

In the operation of the camera, as shown in FIGS. 7-10, the ring gear100 is initially positioned with lug 104 located clockwise of filmengaging member 32 of magazine 16 when the camera is viewed from thetop.

as the hand crank 102 is rotated to move the ring gear in acounterclockwise direction lug 104 engages the member 32, drives ittowards the front of the camera and ejects an image-recording sheet 24from the magazine 16 into the channels 114 and 116 and within the filmengaging surfaces 126 and 128 of gripping member 106. The latter areheld in an open position at this time in accordance with engagement ofthe gripping member against a release lug or trip lug 132 which isfixedly mounted to the left of aperture 14. Continued rotation of thegear ring 100 closes gripping member 106 and draws the image recordingsheet 24 into position at exposure aperture 14 where a conventionalshutter release (not shown) is activated to photoexpose thephotosensitive surface of the sheet. At this time gear ring 100 has beenrotated to the position shown in FIG. 7 wherein actuating lug 104 andgripping member 106 are positioned at the trailing edge of aperture 14.Further rotation of gear ring 104 then draws the film sheet 24 intoposition within processing station 20 and automatically actuates levermember 96 which moves member 62 into engagement with the sheet 24 andpresses its photosensitive surface against the applicator body 76. Theoperator of the camera then presses the dispensing member 82 at the rearof container 64 to inject liquid through applicator 76 to thephotosensitive surface. That is, deformation or the depressing ofportion 82 increases source pressure and applies a positive pressuredifferential between source 68 and surface 78.

In this embodiment, the imbibition time is controlled by the length oftime the operator holds the deformable portion in its depressedcondition. Hence, after a proper interval of, for example, 8 seconds theoperator releases member 82 which elastically tends to return to itsoriginal position. This reduces source pressure and withdraws excessfluid from the vicinity of the film sheet 24. The ring gear 100 is thenfurther rotated to release lever member 96, open the processing station20 and draw film sheet 24 between feed rolls 108 and 110.

As the film sheet 24 enters the feed rolls 108 and 110, it is superposedwithin an image-receiving sheet, dispensed from magazine 18 inaccordance with actuation of its film engaging member 52 by contact withlug 104. Hence, as lug 104 passes across magazine 18 it strikes filmengaging member 52 and drives it along with the moving ring gear 100, asshown in FIG. 9. Consequently film engaging member 52 dispenses animage-receiving sheet 42 in a clockwise direction, that is, toward theprocessing station 20 where a baffle plate 112 forces it around roll 108into engagement with image-recording sheet 24 and between the feed rollin superposition therewith. The operation is completed as shown in FIG.10, when gripper member 106 reaches a position adjoining the trailingedge of magazine 18 where it engages a second release lug or trip lug134. Magazine 18 is then pivoted to an open position for removal of thesuperposed sheets. At this stage of the operation, lug 104 is back toits initial position in readiness for engagement with film engagingmember 32 for dispensing of a second image-recording sheet 24.

For subsequent exposures, the unit is operated in substantially the samemanner, with however, the additional activation of one of theirreversible portions 84. Hence, since a small amount of liquid isimbibed by each film sheet during the processing and applicator body 78will not admit air to the chamber, release of portion 82 withdrawsexcess liquid from the applicator surface 78, but results in reducedpressure on source 68 due to the fluid loss. Consequently, one of theirreversible portions 84 is activated following each application ofprocessing liquid (or just prior to subsequent application) to the filmsheet so as to return the source pressure to its original value wherebyreversible portion 82 will again be ready for dispensing a prescribedamount of liquid to the next successive sheet. Hence, the irreversibleportions are activated to return the source pressure to its originalvalue. Consequently, only portion 82 is depressed for processing of theinitial film sheet whereas portions 84 and 82 are activated in thatorder for processing of subsequent film sheets. It should be understoodthat since the irreversible portions 84 only compensate for theimbibition loss, they need not provide as great a pressure change asthat of portion 82, and hence, may be of smaller area, etc.

Many other variations and different embodiments are possible within thescope of these teachings. For instance, in some applications it may bedesirable to utilize a conventional pump or other means for varying thereservoir pressureso as to provide proper pressure differential acrossthe applicator body. Moreover, various mechanisms for transporting thefilm sheet into position with the applicator member will be suitable anddifferent arrangements for removingair from between the film sheet andthe applicator surface may be employed. For example, the raised surfaceportion of the pressure member may be located along one edge rather thanin the center, or the pressure member may be a substantially planarsurface which is initially contacted against a given edge of the filmsheet and then progessively pressed into contact with the remainder ofthe sheet so as to drive air towards the opposite edge. Additionally,although the applicator body is illustrated as an integral body offilter material, it could of course be a laminated unit having asupporting perforated substrate or supporting base of large porematerial which allows liquid and gas to pass to a thin surface membrane(for example, 140 microns thick) of filter mate rial. In .this case, thesubstrate provides essentially a supporting function while the filtermembrane controls the exclusion of gas. Advantageously, the use ofacomposite body allows efficient operation with a smaller source sinceonly a small amount of liquid is stored in the thin memberane.

Since these and other variations of the invention and its modes ofutilization may be made within the scope of the present teachings, thepreferred embodiment described herein is therefore illustrative and notrestrictive, the scope of the invention being indicated by the appendedclaims and all variations which come within the meaning of the claimsare intended to be embraced therein.

What is claimed is:

l. An apparatus for repetitively dispensing predetermined amountsofliquid from a source of fluid, said apparatus comprising a housingdefining a substantially closed chamber of predetermined volumeconfigured for receiving such source of fluid, said housing includingegress means configured for permitting passage of such liquid betweensaid chamber and the exterior of said housing for dispensing fluidtherefrom while precluding entrance of gaseous fluid thereto, and saidhousing including a plurality of displaceable wall portions adapted tovary said predetermined volume of said chamber in accordance withdisplacement of each of said portions responsive to application of anexternal force thereto, said wall portions being in communication withsaid chamber and configured for independent displacement between a firstposition defining an initial volume of said chamber and a secondposition defining a reduced volume of said chamber thereby providingincreased pressure onsuch fluid within said chamber in accordance withdisplacement from said first to said second position, at least one ofsaid displaceable portions being configured for reversible displacementbetween said first and second positions for dispensing liq uid from saidchamber responsive to displacement of said one portion from said firstto said second position and for subsequently returning any excess ofsuch liquid to said chamber responsive to displacement of said oneportion from said second to said first position, and another of saidportions being configured for irreversible displacement from said firstto said second position for maintaining the pressure within saidcontainer approximately constant intermediate with dispensing suchliquid therefrom responsive to operation of said one portion.

2. An apparatus for repetitively dispensing predetermined amounts offluid from a source contained therein, said apparatus comprising asubstantially rigid housing defining a substantially closed chamber ofpredetermined volame configured for receiving such source of fluid, saidhousing including egress means configured for permitting passage of suchfluid between said chamber and the exterior of said housing fordispensing fluid therefrom, and said housing including a plurality ofdisplaceable wall portions adapted to vary said predetermined volume ofsaid chamber in accordance with displacement of each of said portionsresponsive to application of an external force thereto, said wallportions being in communication with said chamber and configured forindependent displacement between a first position defining an initialvolume of said chamber and a second position defining a reduced volumeof said chamber thereby providing increased pressure on such fluidwithin said chamber in accordance with displacement from said first tosaid second position so as to dispense an appropriate amount of suchfluid through said egress means, at least one of said displaceable wallportions being elastically coupled to said housing such that, uponremoval of an external force configured for displacement of said oneportion from its said first to its said second position, said oneportion tends to automatically return to its original location andthereby tends to return the reduced volume of said container to itsvolume just prior to actuation of said one portion, at least another ofsaid portions is elastically coupled to said body, said another portionincluding means configured for latching said another portion in its saidsecond position following its displacement thereto.

3. An apparatus for repetitively dispensing predetermined amountsofliquid from a source of fluid, said appartus comprising a housingdefining a substantially closed chamber of predetermined volumeconfigured for receiving such source of fluid, said housing includingegress means configured for premitting passage of such fluid betweensaid chamber and the exterior of said housing for dispensing fluidtherefrom, said egress means including a porous filter medium which incooperation with the surface tension of such liquid permits passage ofthe latter while precluding passage of gaseous fluid within a givenrange of pressure differential, and said housing including a pluralityof displaceable wall portions adapted to vary said predetermined volumeof said chamber in accordance with displacement of each of said portionsresponsive to application of an external force thereto, said wallportions being in communication with said chamber and configured forindependent displacement between a first position defining an initialvolume of said chamber and a second position defining a reduced volumeof said chamber thereby providing increased pressure on such fluidwithin said chamber in accordance with displacement from said first tosaid second position, at least one of said displaceable portions beingconfigured for reducing said container volume by a predetermined amountso as to increase the internal pressure within said chamber and toproduce a pressure on the interior of said filter medium which incooperation with the exterior pressure thereof produces a pressuredifferential across said medium which is within said given range ofpressure differential so as to thereby dispense an appropriate amount ofsuch liquid.

4. The apparatus of claim 3 wherein said one of said portions isconfigured for reversible displacement so as to repetitively apply apressure differential across said filter material for repetitivelydispensing such liquid therethrough responsive to repetitive actuationof said one portion.

5. The apparatus of claim 4 wherein including means for latching anotherof said displaceable portions in said second position so as toirreversibly reduce the volume of said chamber whereby said anotherportion may be displaced to its said second position and latched thereinfollowing actuation of said one portion so as to return the internalpressure of said chamber to approximately the initial pressureexistingjust prior to said actuation of said one portion so as tocompensate for the reduced amount of liquid in said chamber.

6. The apparatus of claim 5 wherein said first portion is biased to itssaid first position and said latching means includes an arm memberaffixed to and extending inwardly from said another portion and meanslocated within said housing for cooperating with said arm member whensaid another portion is displaced to its said second position so as toretain it therein.

7. An apparatus for repetitively dispensing predetermined amountsofliquid from a source of fluid, said apparatus comprising:

a housing defining a substantially closed chamber of predeterminedvolume configured for receiving such source of fluid, said housingincluding egress means for permitting passage of such fluid between saidchamber and the exterior of said housing, said egress means includingmeans configured for permitting passage of liquid while precludingpassage of gaseous fluids, and means for selectively reducing saidpredetermined volume of said container in discrete incremental steps soas to repetitively dispense an amount of such fluid through said egressmeans, said volume reducing means includes means operative torepetitively reduce the volume of said chamber by a predetermined amountso as to dispense liquid therefrom and then to tend to return saidvolume to its initial state so as to return any unused portions of suchdispensed liquid to said chamber and means operative to irreversiblyreduce the volume of said chamber to compensate for used portions ofsuch dispensed liquid.

8. The apparatus of claim 7 wherein said housing includes a substantialplanar wall portion forming a wall of said chamber and said volumereducing means includes a plurality of discrete portions of said housingwall which are configured for independent displacement from a firstposition defining said predetermined volume to a second position whichreduces said volume responsive to application of an external force tosaid wall portions.

9. The apparatus of claim 8 wherein said wall portions are initiallysubstantially coplanar with said housing wall when they are located insaid first position and are configured for diplacement inwardly along anaxis substantially perpendicular to said wall.

10. The apparatus of claim 8 wherein at least said one wall portion isbiased to its said first position and configured to automatically returnthereto from its said second position responsive to removal of suchexternal force and thereby tends to return the volume of said containerto its volume just prior to actuation of said one portion.

11. An apparatus for repetitively dispensing predetermined amounts ofliquid from a source thereof, said apparatus comprising:

a housing defining a substantially closed chamber of predeterminedvolume configured for receiving such source of liquid and retaining itat an initial pressure;

egress means located on said housing and configured for passage ofliquid between said chamber and the exterior of said housing andsubstantially precluding passage of gaseous fluid therebetween at leastwhen a given range of pressure is maintained in said chamber;

first means for reversibly varying the volume of said chamber so as tofirst decrease said chamber volume and thereby increase the pressure onsuch source so as to dispense liquid therefrom through said egress meansand then subsequently return said chamber volume to its initial stateexisting just prior to decreasing said volume and thereby decrease thepressure on such source so as to return any unused portion of suchliquid to said chamber; and

second means for irreversibly reducing said chamber volume by a discreteamount following operation of said first means so as to substantiallycompensate for the reduced volume of said source within such chamber andthereby return the pressure of said chamber to approximately saidinitial pressure whereby said first means may be again operated todispense said amount of such liquid and return unused portions thereof.

12. The apparatus of claim 11 wherein said first means and said secondmeans include a plurality of discrete wall portions of said housingwhich are in communication with said chamber and configured fordisplacement between a first position defining said predetermined volumeof said chamber and a second position defining a reduced volume of saidchamber.

1. An apparatus for repetitively dispensing predetermined amounts ofliquid from a source of fluid, said apparatus comprising a housingdefining a substantially closed chamber of predetermined volumeconfIgured for receiving such source of fluid, said housing includingegress means configured for permitting passage of such liquid betweensaid chamber and the exterior of said housing for dispensing fluidtherefrom while precluding entrance of gaseous fluid thereto, and saidhousing including a plurality of displaceable wall portions adapted tovary said predetermined volume of said chamber in accordance withdisplacement of each of said portions responsive to application of anexternal force thereto, said wall portions being in communication withsaid chamber and configured for independent displacement between a firstposition defining an initial volume of said chamber and a secondposition defining a reduced volume of said chamber thereby providingincreased pressure on such fluid within said chamber in accordance withdisplacement from said first to said second position, at least one ofsaid displaceable portions being configured for reversible displacementbetween said first and second positions for dispensing liquid from saidchamber responsive to displacement of said one portion from said firstto said second position and for subsequently returning any excess ofsuch liquid to said chamber responsive to displacement of said oneportion from said second to said first position, and another of saidportions being configured for irreversible displacement from said firstto said second position for maintaining the pressure within saidcontainer approximately constant intermediate with dispensing suchliquid therefrom responsive to operation of said one portion.
 2. Anapparatus for repetitively dispensing predetermined amounts of fluidfrom a source contained therein, said apparatus comprising asubstantially rigid housing defining a substantially closed chamber ofpredetermined volume configured for receiving such source of fluid, saidhousing including egress means configured for permitting passage of suchfluid between said chamber and the exterior of said housing fordispensing fluid therefrom, and said housing including a plurality ofdisplaceable wall portions adapted to vary said predetermined volume ofsaid chamber in accordance with displacement of each of said portionsresponsive to application of an external force thereto, said wallportions being in communication with said chamber and configured forindependent displacement between a first position defining an initialvolume of said chamber and a second position defining a reduced volumeof said chamber thereby providing increased pressure on such fluidwithin said chamber in accordance with displacement from said first tosaid second position so as to dispense an appropriate amount of suchfluid through said egress means, at least one of said displaceable wallportions being elastically coupled to said housing such that, uponremoval of an external force configured for displacement of said oneportion from its said first to its said second position, said oneportion tends to automatically return to its original location andthereby tends to return the reduced volume of said container to itsvolume just prior to actuation of said one portion, at least another ofsaid portions is elastically coupled to said body, said another portionincluding means configured for latching said another portion in its saidsecond position following its displacement thereto.
 3. An apparatus forrepetitively dispensing predetermined amounts of liquid from a source offluid, said appartus comprising a housing defining a substantiallyclosed chamber of predetermined volume configured for receiving suchsource of fluid, said housing including egress means configured forpremitting passage of such fluid between said chamber and the exteriorof said housing for dispensing fluid therefrom, said egress meansincluding a porous filter medium which in cooperation with the surfacetension of such liquid permits passage of the latter while precludingpassage of gaseous fluid within a given range of pressure differential,and said housing inCluding a plurality of displaceable wall portionsadapted to vary said predetermined volume of said chamber in accordancewith displacement of each of said portions responsive to application ofan external force thereto, said wall portions being in communicationwith said chamber and configured for independent displacement between afirst position defining an initial volume of said chamber and a secondposition defining a reduced volume of said chamber thereby providingincreased pressure on such fluid within said chamber in accordance withdisplacement from said first to said second position, at least one ofsaid displaceable portions being configured for reducing said containervolume by a predetermined amount so as to increase the internal pressurewithin said chamber and to produce a pressure on the interior of saidfilter medium which in cooperation with the exterior pressure thereofproduces a pressure differential across said medium which is within saidgiven range of pressure differential so as to thereby dispense anappropriate amount of such liquid.
 4. The apparatus of claim 3 whereinsaid one of said portions is configured for reversible displacement soas to repetitively apply a pressure differential across said filtermaterial for repetitively dispensing such liquid therethrough responsiveto repetitive actuation of said one portion.
 5. The apparatus of claim 4wherein including means for latching another of said displaceableportions in said second position so as to irreversibly reduce the volumeof said chamber whereby said another portion may be displaced to itssaid second position and latched therein following actuation of said oneportion so as to return the internal pressure of said chamber toapproximately the initial pressure existing just prior to said actuationof said one portion so as to compensate for the reduced amount of liquidin said chamber.
 6. The apparatus of claim 5 wherein said first portionis biased to its said first position and said latching means includes anarm member affixed to and extending inwardly from said another portionand means located within said housing for cooperating with said armmember when said another portion is displaced to its said secondposition so as to retain it therein.
 7. An apparatus for repetitivelydispensing predetermined amounts of liquid from a source of fluid, saidapparatus comprising: a housing defining a substantially closed chamberof predetermined volume configured for receiving such source of fluid,said housing including egress means for permitting passage of such fluidbetween said chamber and the exterior of said housing, said egress meansincluding means configured for permitting passage of liquid whileprecluding passage of gaseous fluids, and means for selectively reducingsaid predetermined volume of said container in discrete incrementalsteps so as to repetitively dispense an amount of such fluid throughsaid egress means, said volume reducing means includes means operativeto repetitively reduce the volume of said chamber by a predeterminedamount so as to dispense liquid therefrom and then to tend to returnsaid volume to its initial state so as to return any unused portions ofsuch dispensed liquid to said chamber and means operative toirreversibly reduce the volume of said chamber to compensate for usedportions of such dispensed liquid.
 8. The apparatus of claim 7 whereinsaid housing includes a substantial planar wall portion forming a wallof said chamber and said volume reducing means includes a plurality ofdiscrete portions of said housing wall which are configured forindependent displacement from a first position defining saidpredetermined volume to a second position which reduces said volumeresponsive to application of an external force to said wall portions. 9.The apparatus of claim 8 wherein said wall portions are initiallysubstantially coplanar with said housing wall when they are located insaid first position and are configured for dipLacement inwardly along anaxis substantially perpendicular to said wall.
 10. The apparatus ofclaim 8 wherein at least said one wall portion is biased to its saidfirst position and configured to automatically return thereto from itssaid second position responsive to removal of such external force andthereby tends to return the volume of said container to its volume justprior to actuation of said one portion.
 11. An apparatus forrepetitively dispensing predetermined amounts of liquid from a sourcethereof, said apparatus comprising: a housing defining a substantiallyclosed chamber of predetermined volume configured for receiving suchsource of liquid and retaining it at an initial pressure; egress meanslocated on said housing and configured for passage of liquid betweensaid chamber and the exterior of said housing and substantiallyprecluding passage of gaseous fluid therebetween at least when a givenrange of pressure is maintained in said chamber; first means forreversibly varying the volume of said chamber so as to first decreasesaid chamber volume and thereby increase the pressure on such source soas to dispense liquid therefrom through said egress means and thensubsequently return said chamber volume to its initial state existingjust prior to decreasing said volume and thereby decrease the pressureon such source so as to return any unused portion of such liquid to saidchamber; and second means for irreversibly reducing said chamber volumeby a discrete amount following operation of said first means so as tosubstantially compensate for the reduced volume of said source withinsuch chamber and thereby return the pressure of said chamber toapproximately said initial pressure whereby said first means may beagain operated to dispense said amount of such liquid and return unusedportions thereof.
 12. The apparatus of claim 11 wherein said first meansand said second means include a plurality of discrete wall portions ofsaid housing which are in communication with said chamber and configuredfor displacement between a first position defining said predeterminedvolume of said chamber and a second position defining a reduced volumeof said chamber.